The present invention relates to the technical field for producing cold by applying at least one heat exchanger between a fluid to be cooled or a secondary refrigerant and a refrigerant fluid flowing in one or more units to be cooled of any nature.
More specifically, the present invention relates to the indirect exchange of heat between a refrigerant fluid or refrigerant during vaporization on the one hand and, a fluid to be cooled to the limit of solidification on the other hand, such as a fluid comprising two phases of a same body in melting equilibrium, i.e., comprising a liquid phase and a solid phase, such as for example water added with an antifreeze agent such as salt, alcohol, monoethylene glycol or monopropylene glycol so that its crystallization point is less than 0° C.
In the state of the art, many embodiments of cold-producing machines are known which apply a biphasic fluid to be cooled consisting of a homogenous mixture of liquid and solid phases. For example, Patent EP 0 257 936 describes a cold-producing machine comprising a heat exchange device, formed with a series of exchangers of the type with plates. Each exchanger includes at least one heat exchange wall between the refrigerant fluid and the fluid to be cooled, each flowing in independent circuits. Each heat exchange wall has on one side, a first so-called hot surface in contact with the fluid to be cooled and, on the other side, a second so-called cold surface in contact with the refrigerant fluid.
In order to prevent deposition of a solid layer of the fluid to be cooled, on the first surface of the exchange wall, a doctor blade acting as a mechanical means antagonist to the deposition of this solid layer is displaced in rotation relatively to this first surface. This blade has a sawtooth shape, complementary to the first surface of the heat wall conformed with corrugations.
In practice, the manufacturing processes for the doctor blade and the first surface of the exchange wall proves to be delicate to achieve while having a prohibitive cost. Moreover, insofar as the doctor blade is mounted on a return spring system, a solid layer is able to subsist on the surface of the exchange wall. This scraping effect is all the more reduced since a solid deposit also appears on the doctor blade.
In the same sense, document WO 85/03996 describes a heat exchange device notably including at least one heat exchange wall between a refrigerant fluid and a fluid to be cooled. A beveled or tapered blade in order to exhibit a cutting edge, acts on the heat exchange wall in contact with the fluid to be cooled so as to remove the ice which forms on such a wall. Such a device applying a doctor blade has the same drawbacks as the device described by Patent EP 0 257 936.